1. Field of the Invention
The present invention relates to retinol-modified collagen exhibiting excellent skin anti-aging effects when applied to the skin. More specifically, the present invention relates to retinol-modified collagen which has low toxicity to cells and is excellent in safety without causing itches and the like, enhances the expression of hyaluronic acid synthase genes over an extended time period and increases the production of hyaluronic acid, and also enhances the synthesis of collagen, to thereby produce an excellent effect of preventing wrinkle formation, an excellent effect of improving wrinkles, an excellent effect of making the skin beautiful and an excellent effect of improving skin quality; a method for producing the same, and an external composition for the skin and a sheet-shaped cosmetic each containing the same.
2. Description of the Related Art
Wrinkles in the skin increase as the skin ages. There are wrinkles, for example, thin horizontal wrinkles that develop as deep as the epidermis under the eyes (the epidermis wrinkles), wrinkles that develop as deep as the dermis and appear as fine creases that develop vertically to the mimic muscles in the corners of the eyes, the forehead and the like (dermis wrinkles), and wrinkles that appear as huge creases around the eyes and mouth, in the contours of the face and the like (old age wrinkles). However, there have been no countermeasures that act comprehensively on portions such as the epidermis and dermis, and that provide a multiphase solution to prevent wrinkle formation and to wrinkle improvement.
Meanwhile, collagen or its derivatives are fibrous proteins that may be found in all multicellular organisms, and incorporated in various cosmetics for the purpose of preventing skin aging.
However, conventional collagen or collagen derivatives have a problem of not being able to produce excellent and satisfactory anti skin aging effects.
Accordingly, in light of the existing problems of collagen, the inventors of the present invention have completed an invention relating to polypeptide having a collagen-like structure, and filed an application for the invention (WO 2009/035092).
On the other hand, retinol and its derivatives are a kind of vitamin known to be involved with sustaining, for example, vital functions including visual perception and reproductive functions of normal epithelium tissues such as skin and mucous membrane. They are known as pharmaceuticals for external use for dyskeratosis skin diseases such as ichthyosis vulgaris. Further, retinol derivatives are known to suppress the aging of the skin by sustaining the activities of epithelium tissues and screening the signal transmission of ultraviolet light, and they are widely used as cosmetics for preventing the skin from aging.
However, retinol conventionally reported is toxic to cells, and anti-skin aging effects exhibited by retinol derivatives can not be sustained over an extended time period. Thus, multiphase prevention or improvement of wrinkles can not be carried out. Therefore, development of more effective retinol derivatives and development of active ingredients instead of retinol or its derivatives have been desired.